Hot-water system with axially parallel heat-exchanging tubes



1965 H. VIESSMANN 3, 80,898

HQT-WATER SYSTEM WITH AXIALLY PARALLEL HEAT-EXCHANGING TUBES Filed Jan. 29, 1964 2 Sheets-Sheet 1 .70 van for H. VIESSMANN HOT-WATER SYSTEM WITH AXIALLY PARALLEL HEAT-EXCHANGING TUBES Oct. 25, 1966 2 Sheets$heet 2 Filed Jan. 29, 1964 United States Patent Claims. cl. 165-95) The present invention relates to hot water systems. More specifically, this invention is concerned with a tube joint or connection, particularly for interconnecting the axially parallel tubes of a hot water system, which may be combined in banks or groups for mounting in boilers.

Hot water systems of the type described above are installed in boilers for the purpose of obtaining hot water for industrial uses. Besides the problem of providing suificient space for the banks of tubes, another difficulty that must be considered in the design of such systems is the formation of dirt and scale deposits on the tube walls. Such deposits may become so heavy that the system can be cleaned only by forcing a boring tool through each tube. Cleaning the tubes in this way involves no major difiiculties as long as the tubes are accessible from either end. More work is required, if the tubes are accessible from one end only. In such a case a conventional tube bank has to be removed prior to cleaning. Moreover, the boiler water must be allowed to run out because the conventional tubes are interconnected by headers at one end in which sediments may form also, thereby obstructing the cross-sections of the water ways. To open up and clean the headers, they must be removed along with the banks of tubes.

It is accordingly a primary object of the invention to provide a hot water system in which the tubes may be easily cleaned without the need for removal of headers.

Another object of the invention is to provide means for interconnecting the tubes in such a manner that they may be cleaned without difficulty.

Still another object of the invention is to interconnect the tubes of a hot water system in pairs in such a manner that little space is required by the tube banks in a direction perpendicular to the tubes axes.

A further object of the invention is to provide tube joints for interconnecting the tubes in pairs in parallel relationship.

Still another object of the invention is to provide a tube joint in which the paths of a cleaning tool through the connected tubes partly overlap.

Finally, it is an object of the invention to construct the remote ends of the tubes in such a manner that each remote end of a pair of parallel tubes integrally forms one-half of a return bend, thereby permitting the tubes to be interconnected as by welding without the use of separate tube joints or fittings, whereas the near ends are attached to the boiler wall and accessible.

According to one feature of the invention the inner walls of the tube joint are inclined toward each other. That is, they converge toward the free end of the joint.

According to another feature of the invention the center-to-center distance between the two tubes connected by the tube joint and the wall thickness of the tubes are so chosen that the center-to-center distance does not exceed three times the inner radius of a tube.

The tube joint of the invention has the advantage that the tubes may be arranged in closely spaced relationship, with little space required in a direction perpendicular to the parallel tubes axes. Moreover, both tubes and their connecting joint may be easily cleaned because of the special configuration of the latter.

A further advantage of the invention is that the length of the tubes may be increased over that available with conventional tubes, thereby permit-ting reduction of the number of tubes and, consequently, of the number of tube fittings required for interconnecting the near tube ends at the face of the boiler.

However, it is the most important advantage of the invention that a bank of parallel tubes interconnected by tube joints of the invention may be cleaned without being removed from the boiler. When the tubes and the joints are cleaned, the inclined walls of the latter cause the boring tool to move radially in the joint toward the inside as the tool is forced through the joint, until the tool rod abuts against the tube wall. Thus, sediments and incrustations deposited inside the joint may be removed without difiiculty.

Further objects and features of the invention will be come apparent from the following detailed description of several embodiments of the invention in conjunction with the attached drawings, wherein FIGURE 1 shows a tube joint constructed in accordance with the invention, the view being in section on the plane defined by the axes of the joined tubes;

FIGURE 2 is a sectional view taken along line IIII of FIG. 1;

FIGURE 3 is a sectional view of a bank of parallel tubes mounted in a boiler;

FIGURE 4 shows a plurality of tube fittings of the invention combined to form one unit, and

FIGURE 5 shows another embodiment of the invention in which the principle of the invention is reduced to practice without the use of fittings.

Referring now more particularly to FIG. 1, there are shown respective axial ends of two water or heat-exchanging tubes 2, 3 which are sealingly interconnected by a fitting joint 1 constructed in accordance with the invention. FIG. 2 is a cross-section of fitting joint 1. The inner walls of fitting joint 1 which are perpendicular to the plane defined by the two tube axes have respective inclined portions 4 and 5 and converge toward a bottom portion 6 of the fitting 1 in such a manner that a part 4a, 5a of each portion 4, 5 is axially aligned with that inner wall portion 2a, 3a of the associated tube 2, 3 which is farthest removed from the other tube, whereas another part 4b, 5b of each portion 4, 5 is radially spaced from the corresponding first-mentioned part 4a, 5a toward the other wall portion 5, 4. The centerto-center spacing A of the tubes 2, 3 does not exceed three times the inner radius of each tube 2, 3. The radial spacing of the aligned parts 4a, 5a therefore is not more than five times the radius of the tubes 2, 3.

To illustrate the cleaning of fitting 1, a boring tool is shown in different working positions, 7, 7, and 7". In position 7 the boring tool is shown to operate along the axis of tube 2, until it abuts against the inclined wall portion 4, whence it is forced aside and caused to traverse the fitting obliquely until arriving at position 7.

The diameters of the boring tool, of the tube 2, and of the tool stem 8, and the center-to-center distance A between tubes 2 and 3 are so chosen as to permit the tool to traverse the tube joint beyond the center line 9, as it arrives at its working position 7. Similarly, the working radius of the tool will extend beyond the center line 9, when the tool is in position 7", that is, when it is forced through tube 3. The overlapping paths of the tool cause sediments and incrustations deposited inside the fitting to be removed until a clear passage of adequate flow section in the water ways of the fitting is formed, leaving at most a body of sediment 10 which does not materially impede flow.

FIG. 3 shows two pairs of identical cylindrical water tubes 2, 3 connected by respective joints 1 at their inner ends and having open outer ends sealed in a common tube sheet 11 so that the open orifices of the tubes communicate with a header 12 which is mounted on a boiler shell 13 and is thereby accessible from the outside. Only the tubes 2 of the illustrated pairs of water tubes are visible in the drawing. Access to the tubes 2, 3 for insertion of a cleaning tool 7 may be had by removing the cover of the header 12, but without removing the tube sheet 11, the tubes 2, 3, or their joints 1.

FIG. 4 shows another embodiment of the invention in which a plurality of tube joints are integrally combined to form a block 14. Such an arrangement is particularly useful, when several pairs of parallel tubes are to be mounted side by side. The block 14 has five pairs of openings, and an inner end of a tube 2, 3 is received in each opening.

FIG. shows a further embodiment of the inventionwhich differs from the embodiments described hereinbefore only in that the tube ends 15, 16 are bent and integrally sealingly connected by a weld 17 approximately in the axial plane of symmetry of the joined identical tubes. In this embodiment the same V-shaped flow path is formed as shown in FIGS. 1-4, although the interconnection of the tubes is accomplished without the use of separate tube joints or fittings.

While the novel features of the invention as applied to several preferred embodiments have been shown and described, it will be obvious that modifications of the tube joint may be made without departing from the spirit and the scope of the invention. Accordingly, the scope of this invention is to be governed by the language of the following claims construed in the light of the foregoing description of this invention.

What is claimed as new and desired to be secured by Letters Patent is:

1. A hot water system comprising, in combination:

(a) two tubes having substantially cylindrical inner walls about substantially parallel axes and being axially coextensive substantially over the entire length thereof,

(1) each tube having an open axial end adjacent the open end of the other tube and another axial end; and

(b) a joint sealingly connecting said other axial ends,

(1) said joint having two internal walls transverse to the plane defined by the axes of said tubes, each of said walls having a first axial portion axially aligned with an inner wall portion of a respective one of said tubes farthest.

removed from the other tube, and a second axial portion radially spaced from said first portion in a direction toward the other wall of said joint and axially spaced from said first portion ina direction away from said other end of said respective tube,

(2) the radial spacing of said first portions of said walls not exceeding five times the radius of one of said inner walls of said two tubes, and

(3) said inner walls of said joint tapering toward each other in a direction from the first toward the second portions thereof.

2. A system as set forth in claim 1, wherein said tubes are substantially identical in cross section.

3. A system as set forth in claim 1, wherein said joint is a substantially V-shaped member formed with two juxtaposed openings, said other ends of said tubes being sealingly received in said openings.

4. A system as set forth in claim 1, wherein said joint essentially consists of two substantially identical parts respectively integral with said tubes and sealingly connected to each other.

5. A system as set forth in claim 4, wherein said parts are connected by a weld, said weld extending in a plane substantially parallel to said axes and extending therebetween.

References Cited by the Examiner UNITED STATES PATENTS 643,100 2/1900 Bancroft n 122356 1,889,861 12/1932 Huet 122-355 X 1,960,246 5/1934 Kerr et al. 122360 2,046,569 7/1936 Madorin 122-379 X 2,257,721 9/1941 Dufault 122-356 FOREIGN PATENTS 2,872 of 1890 Great Britain. 135,123 11/1919 Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

CHARLES SUKALO, Assistant Examiner. 

1. A HOT WATER SYSTEM COMPRISING, IN COMBINATION: (A) TWO TUBES HAVING SUBSTANTIALLY CYLINDRICAL INNER WALLS ABOUT SUBSTANTIALLY PARALLEL AXES AND BEING AXIALLY COEXTENSIVE SUBSTANTIALLY OVER THE ENTIRE LENGHT THEREOF, (1) EACH TUBE HAVING AN OPEN AXIAL END ADJACENT THE OPEN END OF THE OTHER TUBE AND ANOTHER AXIAL END; AND (B) A JOINT SEALING CONNECTING SAID OTHER AXIAL ENDS, (1) SAID JOINT HAVING TWO INTERNAL WALLS TRANSVERSE TO THE PLANE DEFINED BY THE AXES OF SAID TUBES, EACH OF SAID WALLS HAVING A FIRST AXIAL PORTION AXIALLY ALIGNED WITH AN INNER WALL PORTION OF A RESPECTIVE ONE OF SAID TUBES FARTHEST REMOVED FROM THE OTHER TUBE, AND A SECOND AXIAL PORTION RADIALLY SPACED FROM SAID FIRST PORTION IN A DIRECTION TOWARD THE OTHER WALL OF SAID JOINT AND AXIALLY SPACED FROM SAID FIRST PORTION IN A DIRECTION AWAY FROM SAID OTHER END OF SAID RESPECTIVE TUBE, (2) THE RADIAL SPACING OF SAID FIRST PORTIONS OF SAID WALLS NOT EXCEEDING FIVE TIMES THE RADIUS OF ONE OF SAID INNER WALLS OF SAID TWO TUBES, AND (3) SAID INNER WALLS OF SAID JOINT TAPERING TOWARD EACH OTHER IN A DIRECTION FROM THE FIRST TOWARD THE SECOND PORTIONS THEREOF. 